Cargo containers need to be inspected at ports and other points of entry or transportation to assess the quantity of contents, quality of contents, and any possible anomalies that may be associated with the contents of these containers, including contraband such as explosives, narcotics, currency, chemical and nuclear weapons. In addition, cargo container inspection is useful for cargo manifest verification. A cargo manifest is a physical or electronic shipping document that accompanies the cargo and provides important descriptive information about the cargo, including bills of lading issued by the carrier or its representative(s), the shipment's cosigner and/or consignee, cargo description, amount, value, origin, and/or destination.
Current security systems are limited in their ability to detect contraband concealed in cargo. Standard and advanced X-ray systems also have difficulty detecting anomalies in break-bulk cargo. Computed Tomography (CT) based systems have been shown to be more suitable for the difficult task of detecting aviation-threat explosives in luggage and, more recently, in larger objects. However, the configuration of commonly employed CT systems prevents scaling the system up to long objects such as large cargo containers, large skids and tankers.
The problem is further compounded by the fact that as a result of the image modulation according to atomic numbers of various materials, it is common for X-ray imaging systems to produce images with dark areas. Although these dark areas might indicate anomalies or presence of threat materials, they yield little information about the exact nature of the anomaly or threat. Also, radiographs produced by conventional X-ray systems are often difficult to interpret because objects are superimposed. Therefore, a trained operator must study and interpret each image to render an opinion on whether or not a target of interest, a threat, is present. Operator fatigue and distraction can compromise detection performance, especially when a large number of such radiographs is to be interpreted, such as at high traffic transit points and ports. Even with automated systems, it becomes difficult to comply with the implied requirement to keep the number of false alarms low, when the system is operated at high throughputs.
This difficulty of inspection is magnified when inspecting larger and oftentimes, cluttered pallets, cargo containers, and cargo-carrying vehicles, such as tanker trucks, which are uniquely designed to carry fluid/liquids or dry bulk loads. Current X-ray inspection systems may not provide an accurate indication of the nature of anomalies present in tankers, which can, among other indications be evidence of theft and/or dilution of tanker contents. An X-ray image itself is insufficient to discern an amount, type, and quality of a commodity within a tanker. These parameters are typically needed to verify a manifest corresponding to the truck, or to ensure that there is no theft underway. There is thus added difficulty in inspection of tanker contents and verification of the manifest.
In addition to reporting the quantity and quality of tanker contents, there is a need to identify and report anomalies associated with the tanker contents. It should be noted that an identified anomaly may end up being contraband as well.
Therefore, there is a need to provide an automated detection system that further includes assistance tools to help operators improve their throughput by scrutinizing cargo images more efficiently, thereby increasing detection and analysis speed. Additionally, an accurate automated content detection and assessment system, such as those for tankers, is needed as a means of preventing theft of tanker contents and as a tool for quality control. Such a tanker content assessment can be a manifest verification tool, and may also have applications in cases when the manifest is not useful. Such applications may include: use at a checkpoint where all passing tankers are expected to be full or empty; to confirm that the tanker content is consistent with expected contents (for example, contents are gasoline and not water); and to check for inner-container alterations including possible alterations made to compartments, walls, and other inner portions of a container/tanker that may be an indication of nefarious intents.
There is also a need for automated detection systems that include assistance tools for detecting the presence specific contraband or threat items, such as currency, drugs, cigarettes and firearms during non-intrusive X-ray imaging of vehicles and cargo. There is also a need for algorithms for processing radiographic images that can be employed to characterize cargo and provide estimates of cargo configuration, such as cargo weight and cargo dimensions, for assisting the operators in detecting illegal items. There is further a need for detection algorithms that enable detection of differences between sequential X-ray inspection images of the same object or vehicle, so that changes in an object or vehicle may be tracked over time or distance traveled.